@Test
public void addReturnsExpectedPosition() {
Position expected = new Position(ROW + 1, COL - 3);
assertEquals(expected, position.add(new Position(1, -3)));
}
@Test
public void addDoesNotAffectOriginalPosition() {
Position clone = position.clone();
position.add(new Position(1, -3));
assertEquals(clone, position);
}